Reappraisal of <i>Didymella macrostoma</i> causing white tip disease of Canada thistle as a new species, <i>Didymella baileyae</i> , sp. nov., and bioactivity of its major metabolites
Bibliographic record
Abstract
Bioherbicides are expected to be a supplement to integrated pest management, assisting in the control of problematic weed species. For instance, bioherbicides (Phoma and BioPhoma) were recently registered in Canada and the USA for the control of some perennial dicotyledonous weeds in lawns. These products are based on strains of the fungus Didymella macrostoma (syn. Phoma macrostoma) that causes white tip disease (WTD) in Canada thistle (Cirsium arvense). In this study, WTD was reported for the first time in the Russian Federation. Analysis of the internal transcribed spacer (ITS) region of nuc rDNA and secondary metabolite profiling confirmed the identity of Russian WTD isolates to Canadian biocontrol strains identified as D. macrostoma. Multilocus phylogenetic analysis based on sequencing of the ITS region, partial large subunit nuc rDNA region (28S), RNA polymerase II second largest subunit gene (rpb2), and partial β-tubulin gene (tub2) has differentiated the WTD isolates from C. arvense and D. macrostoma isolates from other plant hosts. Based on phylogenetic, morphological, and chemotaxonomic features, these WTD isolates were described as a new species named Didymella baileyae, sp. nov. This study also demonstrated the low pathogenicity of the ex-type D. baileyae isolate VIZR 1.53 to C. arvense seedlings and its asymptomatic development in the leaves of aboveground shoots. The organic extracts from mycelium and culture filtrate of D. baileyae, as well as macrocidin A and macrocidin Z, displayed phytotoxicity both to C. arvense leaves and seedlings. Macrocidin A was only detected in the naturally infected leaf tissues of C. arvense showing WTD symptoms. Macrocidins A and Z demonstrated low antimicrobial and cytotoxic activities, exhibiting no entomotoxic properties. The data obtained within this study on the pathogenicity and metabolites of D. baileyae may be important for the rational evaluation of its prospects as a biocontrol agent.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".